The bone conduction speaker generally has a structure with which a vibrating surface of a vibrating member of the bone conduction speaker unit is abutted against an internal surface of a housing, being fixed thereto, thereby the entire housing being vibrated, and the general way of using it is to apply a vibrating surface of the housing to the nipple-like protruded portion, or the like, of an ear (see FIG. 9).
The bone conductive speaker has been developed to provide a hearing support for a conductive hearing-impaired person, however, besides the original application therefor, there is an example of use in which a hearing non-impaired person disposes a bone conduction speaker in the vicinity of a tragus as a means for listening to audio information without plugging up the ear hole. However, in the latter case of usage, there is no problem for communications at a voice level, but the transmission characteristics of bone vibration involves a great attenuation at a high-area side, and thus in listening to music, it is difficult to raise the sound quality of the music.